I am aware of colour gamut limitations, but will my iMAC show sufficient dynamic range for my camera (Leica M9-P), I know this is 'only 11.7' stops or so some will say (Erwin putts recorded higher figures from memory), never realy though about this

I am aware of colour gamut limitations, but will my iMAC show sufficient dynamic range for my camera (Leica M9-P), I know this is 'only 11.7' stops or so some will say (Erwin putts recorded higher figures from memory), never realy though about this

Dynamic range for cameras is the ratio of clipping point to noise floor. Contrast ratio for monitors is the ratio of brightest to darkest display value. It may not make sense to compare those two directly.

It may be as important to worry about display linearity (gamma), as lcd displays are not inherently linear (as cameras are), and measuring/correcting the shadows seems to be non-trivial.

Even a high-DR display will only be able to show its DR in a room with suitable ambient lighting.

I calibrate my display for paper appearance (low brightness, warm whitepoint compared to defaults), and allow daylight into my room. I also use only 8-bits connection to my computer. So I probably dont have that much real CR.

Modern computer monitors may have a regular contrast ratio approaching 1000:1 (10 stops). I believe that prints may have in the range of 100:1 or less (7 stops).

To add to what hjulenissen said above, the majority of sRGB monitors out there have contrast ratios of 500:1 or less (i.e. 8 or 9 stops) at normal viewing brightness (90-120 cd/m2). When you calibrate/profile a monitor some software will report its contrast ratio. My wide gamut Dell U2410 is just about 500:1, while my other monitor, the run of the mill ST2210, clocks in at about 280:1.

Even a high-DR display will only be able to show its DR in a room with suitable ambient lighting.

The core issue seems to be that "black" display pixels will only be as black as charcoal until some clever nano-tech solves it. So light incident on the display will raise black levels without affecting white levels.

Manufacturer specs are always optimistic. Some even provide the dynamic DR, i.e. the difference between max and min lightness after doing adjustments in the device's brightness controls.

I believe that "dynamic DR" is usually used when you have dynamic backlighting (adjusting the backlight dynamically based on the brightest pixel) and/or zoned backlighting (adjusting the lighting within a spatial window in much the same way). Depending on how the measurement is carried out, this can give CR numbers that are very large but may not correlate with user satisfaction.

That is the reason that I wrote "regular contrast ratio" in my initial post.

Quote

I measured my monitor's (HP LP2475W) DR through a simple test based on two patches: white and black. The result under regular daylight lighting conditions was 6,7 stops.

Of course different monitors and adjustments, paper and ink, lighting conditions,... will definitively impact in the achieved DR as perceived by the observer's eye.

Regards

That is interesting. The same (5 years old) monitor is tested here, and DR is reported to be 357/0.45 [cd/m2] = 793:1"The LP2475W was tested at default factory settings out of the box using the LaCie Blue Eye Pro and their accompanying software suite."http://www.tftcentral.co.uk/reviews/hp_lp2475w.htm

So do you use very different display settings (reducing brightness may decrease DR on some monitors), do you pick up more ambient light than tftcentral did, or is there some significant flaw in one of the tests?

So do you use very different display settings (reducing brightness may decrease DR on some monitors), do you pick up more ambient light than tftcentral did, or is there some significant flaw in one of the tests?

Hi,

There is a difference between measuring the light output with an instrument that shields a certain amount of ambient room light (emission only), and a camera shot of the display (emission + ambient). The latter is arguably going to be closer to what we will see ourselves (assuming we don't wear a white shirt which adds light reflection off the screen surface).

I measured mine with a spotmeter. Compared white and black in Photoshop and got EV 1.7 - 8.3 -> 6.6 EV or 1:95

Erik,

Did you measure two different screens, one all white and one all black? That will tell you what more or less what the monitor will do with no one in front of it. If you have two equal patches, one black and one white, on the screen at the same time, that's closer to a realistic test. Taking a typical image and embedding a black and a white square is probably the most realistic, especially if you sit with he meter in your hand where you'd be if you were actually editing.

A large black patch surrounded by a large white area. Used a Minolta Spotmeter F. Made several measurements which were quite consistent.

I think he Spotmeter F measures peak intensity, but I think the results are quite valid in this case.

I repeated the measurements in a dark room, I got 1.8 -- 8.2 EV : 1:83 or 6.4 stops.

I also measured with a very old Minolta Autometer II and got 2.5 -- 8.5 EV, or 1:64 or 6 stops.

I could also mention that I have analyzed quite a lot of raw images using RawDigger and found a single image having a DR more then 9 stops, and that was a dupe I made from a Velvia slide, after shielding out all light leaks. Most images fit comfortably in a 9 stop range and that is mostly due to lens flare. Yes, I can get a DR of 12 stops on a Stouffer wedge but it is no easy.

Did you measure two different screens, one all white and one all black? That will tell you what more or less what the monitor will do with no one in front of it. If you have two equal patches, one black and one white, on the screen at the same time, that's closer to a realistic test. Taking a typical image and embedding a black and a white square is probably the most realistic, especially if you sit with he meter in your hand where you'd be if you were actually editing.

I could also mention that I have analyzed quite a lot of raw images using RawDigger and found a single image having a DR more then 9 stops, and that was a dupe I made from a Velvia slide, after shielding out all light leaks. Most images fit comfortably in a 9 stop range and that is mostly due to lens flare.

Very interesting, I am going to have to check mine. I am curious, did your sample include Exmor sensors and landscapes?

Erik, can you show a 100% view crop of shadow detail brightened in one of the sun shots to show how much meaningful detail is present? Those trailing RGB vertical bars on the shadow end graphed in Rawdigger screengrab is difficult for me to relate EV levels to reproducing what the human eyes see.

Thanks,

Tim

P.S. I appreciate the hard work and effort in your demonstrations and input on this subject.

I looked at some more recent pictures, and found that a landscape image including the sun can have a very excessive DR.

A good recipe may also be a sunrise or sunset picture, with the foreground lighted solely by the dawn/dusk sky. This one has a bit more than 9EV - it's hard to shoehorn that in a goodol'Rebel raw file, and I pityfully underexposed, but can use not having much assistance from the camera as a lame excuse.